As compared with a conventional direct seeding manner, pot seedling transplanting has the following major advantages: growth periods of vegetables can be shortened, crop arrangement is facilitated, land utilization is improved, and economic income is increased. Transplanted pot seedling has a strong root system and consistent flowering and maturation, which can facilitate subsequent stages such as management and harvesting. Therefore, pot seedling cultivation and pot seedling transplanting have become increasingly popular among vegetable producers and flower producers. However, due to the lack of suitable auxiliary machines, pot seedling cultivation and transplanting have been labor intensive industries for a long time, where the labor cost accounts for over 50% of the total production cost. Manual transplanting has high labor intensity, low work efficiency, and low transplanting quality, so that large-area transplantation can hardly be implemented. Consequently, the production scale is small, the production efficiency is low, and the development of related crop production in China is restricted. The transplanter can not only greatly reduce the labor intensity and the production cost, improve the work efficiency, transplanting quality and the survival rate of the pot seedling, but also improve the economic and social benefits. Therefore, there is an urgent need for the development of a system that implements the mechanization of pot seedling transplanting work.
The transplanting system is the core system of the transplanter. The transplanting system is used to plant the pot seedling into the soil by duckbill with better planting quality; the pot seedling comes from the pot seedling distributor or the artificial work. Most vegetable crops need to keep the perpendicularity of the planting pot seedling; it is necessary to ensure the velocity of the relative rest. The theory of zero-speed pot seedling transplanting is to create a moment of relatively static state for each planting pot seedling in the case of continuous movement of the transplanter, in order to complete the planting under the still upright state of the pot seedling. Therefore, in the process of planting pot seedling, the forward speed of the transplanter must be equal to the horizontal velocity of the pot seedling planting moment and the opposite direction, so that the instantaneous absolute velocity of the pot seedling planting moment is zero, the pot seedling is stationary relative to the ground at this point, the pot seedling is planted into the soil by transplanting mechanism, then the soil is overlaid to complete the transplanting process. At present, the transplanter has a slow transplanting speed under the restriction of “zero-speed transplanting”; the transplanting speed is usually about 40 pot seedlings per minute.
A straight line transplanting device for a transplanter was disclosed in the invention patent CN101715670A, including a transmission device, a transplanting device, a control mechanism and a rack, it is used to drill hole, form hole and plant pot seedling. The transmission device comprises sprocket wheels, a gear, a shaft and a crank link mechanism, where the crank link mechanism is composed of a crank, a connecting rod, a push rod, a rack, and bearings. The control mechanism is composed of a stop lever, a positioning plate, a right connecting rod and a left connecting rod, and the bracket is fixed on the rack by bolt connection. The driving power of the crank link mechanism is driven by the sprocket, gear and shaft, and the reciprocating linear motion of the transplanting device is achieved by the motion of crank link mechanism. The transplanting device is in the closed state when it moves to the top dead center. The pot seedling will be put into the transplanting device by the pot seedling feeding device, in the process of the transplanting device drills into the soil near the lower dead center, the transplanting device is opened under the action of the control mechanism, the pot seedling is put into the hole of soil and the transplanting operation is completed. Then the transplanting device is moved upward, the transplanting device is closed under the action of the control mechanism when it reaches a certain height, and the next working cycle will begin. The transplanting device makes reciprocating rectilinear movement in the process of working, which improves the efficiency and reliability of a transplanter. However, the straight-line transplanting device has a velocity in the horizontal direction because it is moving forward with the transplanter, the inertia will cause the transplanting device to produce a scraping to the planted pot seedlings, in this way, the planting pot seedling is not upright and even inverted, the quality of transplanting is reduced, it is also not conducive to the pot seedling growth.
In order to prevent the injury and scraping of the pot seedling caused by the horizontal velocity of the transplanting device, a kind of transplanting mechanism for a dry land transplanter was disclosed in the invention CN101999268A, including a planetary carrier, a center wheel, a planetary wheel I, a planetary wheel II, a connecting rod I, a connecting rod II, rollers, a groove cam and a duckbill transplanting device. By controlling the parameters of planetary gear ratio, CAM groove, a planetary carrier, connecting rod length and difference of connecting rod length, the track of transplanting pot seedlings, receiving, carrying, punching, and transplanting suitable for duckbill transplanting device can be obtained. The pot seedlings planted by the transplanting mechanism designed by the track are well upright and can avoid injury and scraping of the pot seedling. But the structure of this transplanting mechanism is complicated. The pot seedling upright degree can be guaranteed when the relative velocity of the duckbill transplanting device and the ground must be zero. In particular, this transplanting mechanism has a slow transplanting speed and low work efficiency.